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CAMBRIDGE — The final “aha’’ happened at 5:58 a.m. yesterday, in a second-floor classroom at the Massachusetts Institute of Technology, when a ladder was discovered.

After 42 hours, more than 100 puzzles, and very little sleep, team Codex figured out the ladder was part of the MIT Mystery Hunt and used it to find — atop a light fixture — what more than a thousand people had been chasing all weekend: the coin.

The coin meant the team had won this year’s mystery hunt, which comes with a small amount of geek-cred and a huge obligation. Codex must now create next year’s mystery hunt and carry on what has become one of the world’s premier celebrations of the “aha’’ moment.

Since 1980, MIT has been home each January to this very-MIT event in which teams solve highly elaborate puzzles that will lead one team to discover a coin hidden on campus.

But the coin, participants say, is not the real goal. What they chase is the aha moment, the drug of choice for serious puzzle people.

“The aha moment is when you realize how it works, the mechanism,’’ said Aaron Dinkin, the lead puzzle editor this year. “It’s not when it’s solved. It’s when you make the connections that allow you to understand, in principle, how you will solve it.’’

Dinkin’s team, Metaphysical Plant, won last year. He estimates they collectively spent 20,000 hours creating this year’s hunt, making puzzles that involved cryptograms and karaoke, juggling notation and Stephen Colbert, bad celebrity baby names, and the estimated mass of all the popes, in kilograms.

“It’s rare in real life that you get to tackle things that are difficult, fun, and limitless,’’ said Eric Albert, a Newton psychotherapist who is believed to have participated in more hunts than anyone else. “And what makes the hunt work is that it is purely a labor of love. Nobody would put in this kind of work for money.’’

Albert’s team, Palindrome, which featured national puzzle champions and more than a half-dozen crossword puzzle constructors for The New York Times, spent the weekend clustered in two classrooms, suffering intentional intellectual frustration for hours on end in the pursuit of the aha.

“Whenever you get something right, you get a huge endorphin rush,’’ said Arun Sannuti, a librarian who lives in Medford, as he used Google Maps to comb the streets of Paris, searching for graffiti based on classic video games, in attempt to solve one of the puzzles for team Palindrome. “And when that happens, you forget about everything that didn’t go right.’’

Brad Schaefer, a professor of physics and astronomy at Louisiana State University, founded the Mystery Hunt when he was an MIT graduate student. He conceived of it as a campus-wide competition during the Independent Activity Period — four weeks each January when the school gives students the freedom to explore creative projects — and wrote up puzzles that involved such things as breaking a polyalphabetic cipher and translating a Chinese ideogram.

The teams solved them. Quickly. And began what remains a problem to this day: “You just can’t make the problems hard enough,’’ Schaefer said.

In the most famous instance from the early years, Schaefer composed a puzzle in Minoan Linear B, a very old and obscure language, and then checked out all of the MIT library’s books on the subject.

This was long before the Internet, and the teams still had the puzzle solved within hours.

The MIT Mystery Hunt gave birth to an entire genre of multistage puzzle events, and its genetic descendents can now be found at egghead strongholds throughout the world. Stanford hosts a big one, as does Microsoft.

But, according to Schaefer, the modern hunts bear little resemblance to the mimeographed ones of the 1980s, and he marvels at the increasing creativity of the puzzles, which must be not only inventive and challenging, but Google-proof.

“Everything is so ingenious and vibrant,’’ said Schaefer, who often comes to the hunt to help the organizing team run the event. “I’ve slogged through so many Sudokus, and they’re basically all the same. But some of these puzzles are rhapsodically beautiful, and that’s what keeps the solvers coming back for more.’’

As the sun rose yesterday morning and news came into the Palindrome base camp that the coin had been found, there was a combination of disappointment and relief. They’ve won it twice before, and know the work it takes to create a hunt.

“It’s the curse of ‘you won it, you run it,’ ’’ is how Albert describes it.

Seven of them had stayed awake all night. Others were starting to trickle in. Their brains were tired. Some reported slipping into “everything’s a puzzle’’ land, where they overthink everything. It’s a common symptom of the hunt. The organizers spent a good bit of time assuring teams that the baby they had with them was in fact a real baby, and not part of a puzzle.

But there was still time left in the weekend, still unsolved puzzles, and team Palindrome got back to work chasing a few final aha moments.

“The whole idea behind a puzzle is your mind will have this moment where it recognizes something that wasn’t there before,’’ said Foggy Brume, a member of team Palindrome who writes the well-respected puzzle hunt magazine P&A.

“It’s like enjoying a good joke. There’s going to be that one moment of surprise, and that’s what makes the joke. With a puzzle, you want that one aha moment where your mind gets a little reward from it.’’

That’s the drug of puzzles, he said. Then he went looking for it again.